TRADITIONAL POSTER - ismrm

Poster Sessions
2957. T1 Corrected Fast T2 Mapping Using Partially Spoiled SSFP
Oliver Bieri 1 , Klaus Scheffler 1 , Carl Ganter 2
1 Radiological Physics, University of Basel Hospital, Basel, Switzerland; 2 Department of Diagnostic Radiology, Technical University
Munich, Munich, Germany
Only recently a fast method for quantitative T2 mapping was introduced based on partially RF spoiled SSFP sequences (T2-pSSFP). It has been shown that
for large flip angles, estimation of T2 is independent on T1 but becomes sensitive for low to moderate excitation angles. We will show that a correction of
T2-pSSFP with T1 is possible and yields accurate T2 values for flip angles down to 30°. This offers the possibility for acquisitions with higher SNR, but
requires prior knowledge of T1.
2958. Free Breathing Myocardial T2 Measurements
Maelene Lohezic 1,2 , Anne Menini 2,3 , Brice Fernandez 1,2 , Damien Mandry, 2,4 , Pierre-Andre Vuissoz 2,3 ,
Jacques Felblinger 2,3
1 Global Applied Science Lab., GE Healthcare, Nancy, France; 2 IADI, Nancy-Université, Nancy, France; 3 U947, INSERM, Nancy,
France; 4 CHU Nancy, Nancy, France
Myocardial T2 measurements usually require multiple breath hold acquisitions, leading to patient discomfort and misregistrations between images. We
present a new method allowing free breathing T2 quantification that combines respiratory motion estimation, motion compensated reconstruction and T2
calculation. It has been validated on five healthy volunteers and has shown no significant difference compared to the standard breath hold technique. A
morphological proton density weighted image is also obtained, allowing accurate examination of heart structures. Such technique could be used for cardiac
iron overload assessment or detection of early rejection of heart transplant, even in non cooperative patients such as children.
2959. Temporal Phase Correction of Quantitative T 2 Data
Thorarin A. Bjarnason 1 , Cheryl R. McCreary 1 , Jeff F. Dunn 1 , J Ross Mitchell 1
1 University of Calgary, Calgary, AB, Canada
Magnetic resonance images are formed typically by taking the magnitude of reconstructed complex values. The magnitude operation changes the noise
distribution from Gaussian to Rician. This operation causes artifacts in T 2 distributions calculated using the non-negative least squares algorithm. The
artifacts caused by non-Gaussian noise distributions are becoming more relevant as scientists begin to identify tissue compartments with small intensity long
T 2 decays. Here we propose, and examine, a temporal phase correction method allowing T 2 distributions to be created from complex quantitative T 2 data.
2960. T2 Mapping Using T2prepared-SSFP: Optimizing Echo Time, Flip Angle and Parameter Fitting
Shivraman Giri 1 , YiuCho Chung 2 , Saurabh Shah 2 , Hui Xue 3 , Jens Guehring 3 , Sven Zuehlsdorff 2 , Orlando P.
Simonetti
1 The Ohio State University, Columbus, OH, United States; 2 Siemens Healthcare; 3 Siemens Corporate Research
In this study, we analyze the effect of flip angles and choice of T2Prep times in T2 quantification using Magnetization prepared balanced SSFP sequence.
2961. Making High Resolution T2 and T2* Maps Through the Use of Accelerated Gradient-Echo
Asymmetric Spin-Echo (GREASE) Pulse Sequences
Daniel Lee Shefchik 1 , Andrew Scott Nencka 1 , Andrzej Jesmanowicz 1 , James S. Hyde 1
1 Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States
The gradient-echo asymmetric spin-echo pulse sequence (GREASE) allows for the production of T2 and T2* maps. In order to obtain high resolution maps,
while maintaining signal, the GREASE sequence was modified to accelerate the acquisition of the images three different ways. The modifications included
partial k-space GREASE [2], generalized autocalibrating partially parallel acquisitions (GRAPPA) Grease [3], and partial k-space GRAPPA GREASE. The
sequences are implemented and compared to the original GREASE sequence to determine the best technique to obtain quality T2 and T2* maps.
2962. R2/R2* Estimation Errors in Combined Gradient- And Spin-Echo EPI Sequences Due to Slice-Profile
Differences Between RF Pulses
Heiko Schmiedeskamp 1 , Matus Straka 1 , Roland Bammer 1
1 Lucas Center, Department of Radiology, Stanford University, Stanford, CA, United States
There is an increased interest in combined gradient-echo and spin-echo pulse sequences for applications in PWI and fMRI, facilitated by the differences in
signal decay of gradient echoes and spin echoes depending on the mean vessel size within a voxel. This abstract deals with issues of mismatched slice
profiles in such pulse sequences between the 90° excitation pulse and the 180° refocusing pulse, and it introduces a scaling factor for improved T1-
independent R2 and R2* quantification.
2963. Multi Echo Spiral Imaging : Optimized K-Space Trajectories for T2* Quantification.
Nicolas Pannetier 1,2 , Mohamed Tachrount 1,2 , Christoph Segebarth 1,2 , Emmanuel Louis Barbier 1,2 , Laurent
Lamalle 3
1 Inserm, U836, Grenoble, France; 2 Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR-S836, Grenoble, France;
3 IFR n°1, INSERM, Grenoble, France
Effective and theoretical k-space trajectories differ due to eddy currents or gradient hardware imperfections. In this study we propose a fast two steps
approach to optimized k-space trajectories in multi-echo spiral imaging. Once optimized, images were acquired on rat brain and T2* map was estimated.